CVE-2025-31266 is a security vulnerability identified in Apple macOS Safari browser that allows a malicious website to spoof the domain name shown in the title of a pop-up window. The root cause is insufficient truncation and validation of the fully qualified domain name when rendering the pop-up window title, enabling attackers to craft deceptive titles that appear to originate from trusted domains. This spoofing can trick users into believing they are interacting with legitimate sites, facilitating phishing, credential theft, or social engineering attacks. The vulnerability was addressed by Apple through improved truncation logic in Safari 18.5 and macOS Sequoia 15.5. The affected versions are unspecified but include earlier Safari and macOS releases prior to these updates. There are no known exploits in the wild at the time of publication. The vulnerability does not require user authentication but does require user interaction with the pop-up window. The impact is primarily on user trust and confidentiality, as attackers can manipulate visual cues to deceive users. The vulnerability does not directly compromise system integrity or availability but can be leveraged as part of broader attack chains. This issue highlights the importance of proper UI element validation to prevent domain spoofing in browser interfaces.

For European organizations, this vulnerability poses a risk primarily to user confidentiality and trust. Attackers exploiting this flaw can conduct sophisticated phishing campaigns by presenting spoofed pop-up windows that appear to originate from legitimate domains, potentially leading to credential theft, unauthorized access, or malware installation. Sectors with high reliance on macOS devices and Safari browser, such as creative industries, finance, and government agencies, may face increased exposure. The vulnerability could undermine secure communications and increase the likelihood of successful social engineering attacks. Although it does not directly affect system integrity or availability, the indirect consequences of compromised credentials or user deception can lead to significant operational and reputational damage. Organizations with remote or hybrid workforces using macOS devices are particularly vulnerable. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time.

European organizations should prioritize updating all macOS devices to at least macOS Sequoia 15.5 and Safari to version 18.5 or later to ensure the vulnerability is patched. IT departments should enforce update policies and verify compliance through endpoint management tools. User awareness training should be enhanced to educate employees about the risks of spoofed pop-up windows and the importance of verifying domain authenticity before entering sensitive information. Implementing browser security extensions or tools that highlight domain information more clearly can help users detect spoofing attempts. Network-level protections such as web filtering and anti-phishing solutions should be configured to detect and block malicious websites attempting to exploit this vulnerability. Organizations should monitor security advisories for any emerging exploits and be prepared to respond quickly. Additionally, consider restricting the use of Safari for sensitive operations until patches are applied, or use alternative browsers with mitigations against similar spoofing attacks.